A nano-magnetic flocculant, a preparation method and application thereof

Abstract

The application discloses a kind of nano magnetic flocculants and its preparation method and application, belong to drinking water processing technical field, including the following steps: step S1, modified ferroferric oxide nanosphere is ultrasonically dispersed in ammonia alcohol solution, while stirring, slowly drop adding tetraethyl orthosilicate, continue stirring after drop, after centrifugal separation, wash, obtain silica coated ferroferric oxide nanoparticles;Step S2, phenylalanine modified chitosan is added into glacial acetic acid solution, after completely swelling and dissolving, add silica coated ferroferric oxide nanoparticles and ultrasonic treatment, under low pressure ultraviolet lamp, then with anhydrous ethanol wash purification, vacuum drying to constant weight, obtain nano magnetic flocculants;The method of the application is simple and easy to operate, the nano magnetic flocculants prepared can be quickly adsorbed to the surface of sulfonamide antibiotics, produce flocculation and can be magnetically separated, very suitable for trace sulfonamide antibiotics in drinking water source efficient removal.

Description

A nano-magnetic flocculant, its preparation method and application Technical Field

[0001] This invention belongs to the field of drinking water treatment technology, specifically relating to a nano-magnetic flocculant, its preparation method, and its application. Background Technology

[0002] With the development of animal husbandry and aquaculture, the types and amounts of antibiotics used have increased significantly. After use, antibiotics can enter the aquatic environment through various pathways. In recent years, sulfonamide antibiotics have been detected in drinking water sources at high concentrations, polluting drinking water and threatening public health and safety. While conventional treatment processes in existing drinking water plants are effective at removing large molecules, they lack specificity for emerging pollutants like sulfonamide antibiotics, resulting in poor removal efficiency. When treating raw water containing trace amounts of sulfonamide antibiotics, existing flocculants fail to form strong interactions within the flocs, limiting their treatment efficiency to below 60%. Therefore, improvements to existing flocculants are needed to enhance the interaction between flocculants and sulfonamide antibiotics. Summary of the Invention

[0003] The purpose of this invention is to provide a nano-magnetic flocculant, its preparation method, and its application, in order to solve the problems in the background art.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A method for preparing a nano-magnetic flocculant includes the following steps:

[0006] Step S1: The modified iron oxide nanospheres were ultrasonically dispersed in an ammonia-ethanol solution. While mechanically stirring, tetraethyl orthosilicate was slowly added dropwise. After the addition was completed, stirring was continued for 24 hours. After centrifugation, the nanospheres were washed several times with distilled water and anhydrous ethanol to obtain silicon dioxide-coated iron oxide nanoparticles.

[0007] Step S2: Add phenylalanine-modified chitosan to glacial acetic acid solution. After complete swelling and dissolution, add silica-coated iron oxide nanoparticles and sonicate for 10 min. Irradiate under a low-pressure ultraviolet lamp for 2-3 h. Then wash and purify with anhydrous ethanol 6-8 times. Vacuum dry at 60℃ to constant weight to obtain nano-magnetic flocculant.

[0008] Furthermore, the modified iron oxide nanospheres are prepared through the following steps;

[0009] Ferric oxide nanoparticles were dispersed in deionized water, then hydrochloric acid solution and sodium citrate solution were added and stirred for 2-3 hours to modify the surface of the ferric oxide nanoparticles. After magnetic filtration, the nanoparticles were washed several times with anhydrous ethanol and distilled water to obtain modified ferric oxide nanospheres. Sodium citrate adsorbed on the surface of the ferric oxide nanoparticles changed their surface potential, which is beneficial for the ferric oxide nanoparticles to overcome the magnetic dipole moment.

[0010] Furthermore, the ratio of the iron oxide nanoparticles, deionized water, hydrochloric acid solution, and sodium citrate solution is 0.15-2g:50mL:10mL:100mL; the concentration of the hydrochloric acid solution is 2mol / L; and the concentration of the sodium citrate solution is 0.5mol / L.

[0011] Furthermore, the ratio of the modified iron oxide nanospheres, ammonia-ethanol solution, and tetraethyl orthosilicate is 0.15-2g: 45-46mL: 0.45mL; the ammonia-ethanol solution is composed of 25wt% ammonia and ethanol mixed at a volume ratio of 1:75.

[0012] Furthermore, the phenylalanine-modified chitosan is prepared through the following steps:

[0013] Chitosan was added to hydrochloric acid solution and stirred to dissolve. The pH of the solution was then adjusted to 5-6. The mixture was added and stirred for 2 hours. Phenylalanine solution was added dropwise and the mixture was stirred magnetically at 25°C for 4 hours. The reaction product was poured into acetone to precipitate, filtered, washed, and vacuum dried for 24 hours to obtain phenylalanine-modified chitosan.

[0014] Further, the ratio of chitosan, hydrochloric acid solution, mixed solution and phenylalanine solution is 1g:100mL:18-20mL:100mL; the concentration of hydrochloric acid solution is 1wt%; and the concentration of phenylalanine solution is 0.5wt%.

[0015] Further, the mixed solution is obtained by mixing and dissolving 4-dimethylaminopyridine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N,N-dimethylformamide in a ratio of 0.1-0.2g:0.1-0.2g:20mL.

[0016] Furthermore, the ratio of the amount of phenylalanine-modified chitosan, glacial acetic acid solution, and silica-coated iron oxide nanoparticles is 1.5g:15mL:2g; the concentration of the glacial acetic acid solution is 1wt%.

[0017] A nano-magnetic flocculant is prepared by the above method.

[0018] The application of a nanomagnetic flocculant in removing trace amounts of sulfonamide antibiotics from drinking water sources includes the following steps:

[0019] The nano-magnetic flocculant was added to the raw water from the drinking water source at a dosage of 10-12 mg / L. After stirring and mixing for 5-10 minutes, the mixture was allowed to stand and settle for 2 hours. After magnetic separation of the flocs, the removal of trace amounts of sulfonamide antibiotics from the drinking water source was completed.

[0020] The beneficial effects of this invention are:

[0021] This invention modifies the surface of iron oxide nanoparticles with sodium citrate to obtain modified iron oxide nanospheres, which not only improve dispersibility by changing their surface potential but also help overcome magnetic dipole moments. Then, by adding tetraethyl orthosilicate solution, silica-coated iron oxide nanoparticles are prepared. Coating magnetic iron oxide nanoparticles with silica improves their stability and also enhances their adsorption performance. Finally, under ultraviolet light irradiation, the silica-coated iron oxide nanoparticles are grafted with phenylalanine-modified chitosan to obtain a nano-magnetic flocculant. The phenylalanine groups in the phenylalanine-modified chitosan can react with sulfonamides... Electrostatic attraction, π-electron interactions, and hydrogen bonding between antibiotic molecules promote the adsorption bridging and entrapment sweeping effects of the nano-magnetic flocculant, thus enhancing the removal efficiency of sulfonamide antibiotics from drinking water sources. The amino groups in the chitosan molecule also readily combine with the benzene rings in sulfonamide antibiotic molecules. Therefore, under the combined effect of these factors, the nano-magnetic flocculant of this invention can rapidly adsorb onto the surface of sulfonamide antibiotics, further generating flocculation, and ultimately rapidly separating the flocs under the action of a magnetic field. Therefore, the nano-magnetic flocculant of this invention is highly suitable for the efficient removal of trace amounts of sulfonamide antibiotics from drinking water sources, achieving a removal rate of up to 90%, and its preparation method is simple and easy to operate. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1

[0024] A method for preparing a nano-magnetic flocculant includes the following steps:

[0025] Step S1: Disperse 0.15g of iron oxide nanoparticles into 50mL of deionized water, then add 10mL of 2mol / L hydrochloric acid solution and 100mL of 0.5mol / L sodium citrate solution and stir for 2h. After magnetic filtration, wash three times with anhydrous ethanol and distilled water to obtain modified iron oxide nanospheres.

[0026] Step S2: 0.15g of modified iron oxide nanospheres were ultrasonically dispersed in 45mL of ammonia-ethanol solution. The ammonia-ethanol solution was composed of 25wt% ammonia and ethanol mixed at a volume ratio of 1:75. While mechanically stirring, 0.45mL of tetraethyl orthosilicate was slowly added dropwise. After the addition was completed, stirring was continued for 24h. After centrifugation, the nanospheres were washed three times with distilled water and anhydrous ethanol to obtain silica-coated iron oxide nanoparticles.

[0027] Step S3: Add 1g of chitosan to 100mL of 1wt% hydrochloric acid solution and stir to dissolve. Then adjust the pH of the solution to 6, and add 18mL of mixed solution and stir to react for 2h. The mixed solution is obtained by mixing and dissolving 4-dimethylaminopyridine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N,N-dimethylformamide in a ratio of 0.1g:0.1g:20mL. Add 100mL of 0.5wt% phenylalanine solution dropwise and stir magnetically at 25℃ for 4h. Pour the reaction product into acetone to precipitate, filter and wash, and vacuum dry for 24h to obtain phenylalanine modified chitosan.

[0028] Step S4: Add 1.5g of phenylalanine-modified chitosan to 15mL of 1wt% glacial acetic acid solution. After complete swelling and dissolution, add 2g of silica-coated iron oxide nanoparticles and sonicate for 10min. Irradiate under a low-pressure ultraviolet lamp for 2h. Then wash and purify 6 times with anhydrous ethanol and vacuum dry at 60℃ to constant weight to obtain nano-magnetic flocculant.

[0029] Example 2

[0030] A method for preparing a nano-magnetic flocculant includes the following steps:

[0031] Step S1: Disperse 0.18g of iron oxide nanoparticles into 50mL of deionized water, then add 10mL of 2mol / L hydrochloric acid solution and 100mL of 0.5mol / L sodium citrate solution and stir for 2h. After magnetic filtration, wash three times with anhydrous ethanol and distilled water to obtain modified iron oxide nanospheres.

[0032] Step S2: 0.18 g of modified iron oxide nanospheres were ultrasonically dispersed in 45 mL of ammonia-ethanol solution. The ammonia-ethanol solution was composed of 25 wt% ammonia and ethanol mixed at a volume ratio of 1:75. While mechanically stirring, 0.45 mL of tetraethyl orthosilicate was slowly added dropwise. After the addition was completed, stirring was continued for 24 h. After centrifugation, the nanospheres were washed three times with distilled water and anhydrous ethanol to obtain silica-coated iron oxide nanoparticles.

[0033] Step S3: Add 1g of chitosan to 100mL of 1wt% hydrochloric acid solution and stir to dissolve. Then adjust the pH of the solution to 5, and add 20mL of mixed solution and stir to react for 2h. The mixed solution is obtained by mixing and dissolving 4-dimethylaminopyridine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N,N-dimethylformamide in a ratio of 0.15g:0.15g:20mL. Add 100mL of 0.5wt% phenylalanine solution dropwise and stir magnetically at 25℃ for 4h. Pour the reaction product into acetone to precipitate, filter and wash, and vacuum dry for 24h to obtain phenylalanine modified chitosan.

[0034] Step S4: Add 1.5g of phenylalanine-modified chitosan to 15mL of 1wt% glacial acetic acid solution. After complete swelling and dissolution, add 2g of silica-coated iron oxide nanoparticles and sonicate for 10min. Irradiate under a low-pressure ultraviolet lamp for 3h. Then wash and purify 7 times with anhydrous ethanol and vacuum dry at 60℃ to constant weight to obtain nano-magnetic flocculant.

[0035] Example 3

[0036] A method for preparing a nano-magnetic flocculant includes the following steps:

[0037] Step S1: Disperse 2g of iron oxide nanoparticles into 50mL of deionized water, then add 10mL of 2mol / L hydrochloric acid solution and 100mL of 0.5mol / L sodium citrate solution and stir for 3h. After magnetic filtration, wash three times with anhydrous ethanol and distilled water to obtain modified iron oxide nanospheres.

[0038] Step S2: 2g of modified iron oxide nanospheres were ultrasonically dispersed in 46mL of ammonia-ethanol solution. The ammonia-ethanol solution was composed of 25wt% ammonia and ethanol mixed at a volume ratio of 1:75. While mechanically stirring, 0.45mL of tetraethyl orthosilicate was slowly added dropwise. After the addition was completed, stirring was continued for 24h. After centrifugation, the nanospheres were washed three times with distilled water and anhydrous ethanol to obtain silica-coated iron oxide nanoparticles.

[0039] Step S3: Add 1g of chitosan to 100mL of 1wt% hydrochloric acid solution and stir to dissolve. Then adjust the pH of the solution to 6, and add 20mL of mixed solution and stir to react for 2h. The mixed solution is obtained by mixing and dissolving 4-dimethylaminopyridine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N,N-dimethylformamide in a ratio of 0.2g:0.2g:20mL. Add 100mL of 0.5wt% phenylalanine solution dropwise and stir magnetically at 25℃ for 4h. Pour the reaction product into acetone to precipitate, filter and wash, and vacuum dry for 24h to obtain phenylalanine modified chitosan.

[0040] Step S4: Add 1.5g of phenylalanine-modified chitosan to 15mL of 1wt% glacial acetic acid solution. After complete swelling and dissolution, add 2g of silica-coated iron oxide nanoparticles and sonicate for 10min. Irradiate under a low-pressure ultraviolet lamp for 3h. Then wash and purify 8 times with anhydrous ethanol and vacuum dry at 60℃ to constant weight to obtain nano-magnetic flocculant.

[0041] Comparative Example 1

[0042] The difference between this comparative example and Example 3 is that step S2 is not performed, and the modified iron oxide nanospheres are not coated with silica; all other steps are the same.

[0043] Comparative Example 2

[0044] The difference between this comparative example and Example 3 is that step S3 is not performed, and the chitosan is not modified with phenylalanine; all other steps are the same.

[0045] Example 4

[0046] This embodiment provides an application of a nano-magnetic flocculant for removing trace amounts of sulfonamide antibiotics from drinking water sources, including the following steps:

[0047] The nano-magnetic flocculant prepared in Example 1 was added to the raw water taken from the drinking water source at a dosage of 10 mg / L. The sulfonamide antibiotic in the raw water was sulfadiazine. After stirring and mixing for 5 min, the mixture was allowed to stand and settle for 2 h. After magnetic separation of the flocs, the removal of trace sulfonamide antibiotics from the drinking water source was completed.

[0048] Example 5

[0049] This embodiment provides an application of a nano-magnetic flocculant for removing trace amounts of sulfonamide antibiotics from drinking water sources, including the following steps:

[0050] The nano-magnetic flocculant prepared in Example 2 was added to the raw water taken from the drinking water source at a dosage of 11 mg / L. The sulfonamide antibiotic in the raw water was sulfadiazine. After stirring and mixing for 8 minutes, the mixture was allowed to stand and settle for 2 hours. After magnetic separation of the flocs, the removal of trace sulfonamide antibiotics from the drinking water source was completed.

[0051] Example 6

[0052] This embodiment provides an application of a nano-magnetic flocculant for removing trace amounts of sulfonamide antibiotics from drinking water sources, including the following steps:

[0053] The nano-magnetic flocculant prepared in Example 3 was added to the raw water taken from the drinking water source at a dosage of 12 mg / L. The sulfonamide antibiotic in the raw water was sulfadiazine. After stirring and mixing for 10 min, the mixture was allowed to stand and settle for 2 h. After magnetic separation of the flocs, the removal of trace sulfonamide antibiotics from the drinking water source was completed.

[0054] Comparative Example 3

[0055] Compared with Example 6, this comparative example uses an equal amount of commercially available polyaluminum chloride flocculant to replace the nano-magnetic flocculant prepared in Example 3, while the other steps are the same.

[0056] Comparative Example 4

[0057] Compared with Example 6, this comparative example uses an equal amount of the nano-magnetic flocculant prepared in Comparative Example 1 to replace the nano-magnetic flocculant prepared in Example 3, while the other steps are the same.

[0058] Comparative Example 5

[0059] Compared with Example 6, this comparative example uses an equal amount of the nano-magnetic flocculant prepared in Comparative Example 2 to replace the nano-magnetic flocculant prepared in Example 3, while the other steps are the same.

[0060] The concentrations of sulfonamide antibiotics in the raw water before and after flocculation treatment in Examples 4-6 and Comparative Examples 3-5 were measured using liquid chromatography-mass spectrometry (LC-MS). The removal rates of sulfonamide antibiotics in each treatment group were recorded and calculated. The results are shown in Table 1.

[0061] Table 1

[0062]

[0063] As can be seen from the data in Table 1, the nano-magnetic flocculant prepared in this invention has excellent removal effect on trace amounts of sulfonamide antibiotics in drinking water sources, with a removal rate of over 90%, showing significant advantages compared to existing polyaluminum chloride flocculants. The coating treatment of modified iron oxide nanospheres with silica and the modification of chitosan with phenylalanine can synergistically promote each other, improving the removal effect and efficiency of sulfonamide antibiotics in drinking water sources.

[0064] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nano-magnetic flocculant, characterized in that, Includes the following steps: Step S1: Modified iron oxide nanospheres are ultrasonically dispersed in an ammonia-ethanol solution. Tetraethyl orthosilicate is slowly added dropwise while stirring. After the addition is complete, stirring continues for 24 hours. After centrifugation, the nanospheres are washed several times with distilled water and anhydrous ethanol to obtain silica-coated iron oxide nanoparticles. The modified iron oxide nanospheres are prepared by the following steps: iron oxide nanoparticles are dispersed in deionized water, then hydrochloric acid solution and sodium citrate solution are added and stirred for 2-3 hours. After magnetic filtration, the mixture is washed with anhydrous ethanol and distilled water to obtain modified iron oxide nanospheres. Step S2: Phenylalanine-modified chitosan is added... In glacial acetic acid solution, after complete swelling and dissolution, silica-coated iron oxide nanoparticles are added and ultrasonically treated for 10 min, then irradiated under a low-pressure ultraviolet lamp for 2-3 h, and then washed and purified with anhydrous ethanol, and vacuum dried to constant weight to obtain nano-magnetic flocculant; wherein, the phenylalanine-modified chitosan is prepared by the following steps: chitosan is added to hydrochloric acid solution and stirred to dissolve, then the pH of the solution is adjusted to 5-6, and then the mixed solution is added and stirred for 2 h, then phenylalanine solution is added dropwise, and the reaction is magnetically stirred at 25℃ for 4 h, the reaction product is poured into acetone to precipitate, filtered and washed, and vacuum dried to obtain phenylalanine-modified chitosan.

2. The method for preparing a nano-magnetic flocculant according to claim 1, characterized in that, The ratio of the iron oxide nanoparticles, deionized water, hydrochloric acid solution, and sodium citrate solution is 0.15-2g:50mL:10mL:100mL; the concentration of the hydrochloric acid solution is 2mol / L; and the concentration of the sodium citrate solution is 0.5mol / L.

3. The method for preparing a nano-magnetic flocculant according to claim 1, characterized in that, The ratio of the modified iron oxide nanospheres, ammonia-ethanol solution, and tetraethyl orthosilicate is 0.15-2:45-46:0.45 mL; the ammonia-ethanol solution is composed of 25 wt% ammonia and ethanol mixed at a volume ratio of 1:

75.

4. The method for preparing a nano-magnetic flocculant according to claim 1, characterized in that, The ratio of chitosan, hydrochloric acid solution, mixed solution and phenylalanine solution is 1g:100mL:18-20mL:100mL; the concentration of hydrochloric acid solution is 1wt%; and the concentration of phenylalanine solution is 0.5wt%.

5. The method for preparing a nano-magnetic flocculant according to claim 1, characterized in that, The mixed solution was obtained by mixing and dissolving 4-dimethylaminopyridine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N,N-dimethylformamide in a ratio of 0.1-0.2g:0.1-0.2g:20mL.

6. The method for preparing a nano-magnetic flocculant according to claim 1, characterized in that, The ratio of phenylalanine-modified chitosan, glacial acetic acid solution, and silica-coated iron oxide nanoparticles is 1.5g:15mL:2g; the concentration of the glacial acetic acid solution is 1wt%.

7. A nano-magnetic flocculant, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. The application of the nanomagnetic flocculant according to claim 7 in removing trace amounts of sulfonamide antibiotics from drinking water sources.

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